Toyoda Koki Kabushiki Kaisha

Toyota Jidosha Kogyo Kabushiki Kaisha

Jtekt Corporation

Toyota Jidosha Kabushiki Kaisha

Toyoda Koki Kabushiki K.

Mikio Suzuki

Yoshiharu Inaguma

Kyosuke Haga

Katsuhisa Mori

Susumu Honaga

Hideya Kato

Kenichi Fukumura

Minoru Kawabata

Keiichi Nakamura

Masaya Segi

Masaru Suzuki

Masaaki Hayashi

Hiroshi Suzuki

Keiji Suzuki

Shigeo Iwashita

Koichi Takanishi

Yukio Kondo

Yoshinori Kaneda

Yutaka Mori

Akiharu Abe

Akio Numazawa

Kunihiko Eto

Yasunori Nakawaki

Yoshiyuki Takeuchi

Hiroki Sato

Hiroshi Kawakami

Kaori Fujita

Kenichi Kikuchi

Osamu Watanabe

Shigeo Tanooka

Kiyotaka Kato

Kenji Takahashi

Tsuyoshi Ikeda

Masato Tanabe

Satoshi Suto

Ryutaro Abe

Masanori Natsume

Ikuo Okuda

Hironori Hibino

Hideaki Sugiyama

Hirotaka Shibata

Masanari Torii

A solenoid valve comprises a solenoid portionand a valve portion. The solenoid portionis constructed by a stator core, an electromagnetic coiland a plunger. The valve portionis constructed by a valve sleeveand a spoolaxially forming plural lands-in series. The plungeris axially moved by electromagnetic attraction and drives the spool. There are formed the same pressurized areas at the plungerand the land of the spoolclosest to the plunger. Therefore, the volume in an intermediate space B between the plungerand the spoolis constant and contaminants in the oil are not sucked into the intermediate space B.

Solenoid valve

In a solenoid valve, an annular oil grooveis formed at a portion corresponding to a spring chamberon the external surface of a sleeve, a drain passageis formed to make an upper part of the annular oil groovecommunicate with the outside of an insertion bore, and a throttle holeis provided at a lower part of the annular oil groovefor making the annular oil groovecommunicate with the spring chamber. Since the annular oil groovecommunicates with the outside of the insertion boreat its upper part through the drain passage, it can be realized to store the operating oil to the height of the upper part of the annular oil groove, so that the operating oil can be reserved in the spring chamberwhich communicates with the annular oil groove through the throttle hole. Further, the operating oil is supplied from a feedback portnext to the spring chamberthrough a clearance between the spool valveand a valve hole. Thus, the solenoid valveis able to secure the damping effect of the working oil on the spool valveand a plungerand to suppress the self oscillation even while being operated in the atmosphere for a long time.

In a hydraulic pump, a cam ring is provided in a cylindrical adaptor for movement in a radial direction, and a differential pressure control valve is provided to control internal pressure and load pressure at the front and back sides of a variable orifice to be introduced into action chambers and formed at the opposite sides of the cam ring for controlling a discharge amount of the pump in accordance with the rotation speed of the pump. The differential pressure control valve is operated under the internal pressure and load pressure respectively introduced into action chambers and the load of a thrust spring biasing the differential pressure control valve toward the internal pressure chamber. The load of the thrust spring is increased or decreased in accordance with an increase or a decrease of the load pressure. The increase or decrease of the load pressure is effected by a load pressure responsive piston loaded by a thrust spring and engaged with the differential pressure control valve at one end thereof in the internal pressure chamber.

Variable displacement pump

Disclosed is a solenoid-operated valve which hardly brings a plunger into a lock and is capable of improving its responsivety. In the solenoid-operated valve, the plunger slidably guided in an inner bore formed in a yoke and a core aligned axially is moved by energizing an electromagnetic coil, and a spool in a valve section is moved through a rod portion which protrudes from an end of the plunger to pass through a center hole of the core. An electromagnetic section fluid chamber defined by a forward end surface of the plunger and the inner bore of the core communicates with an intermediate fluid chamber defined between the core and a valve sleeve, through a clearance between the center hole and rod portion. The spool is provided at one end thereof with a land portion whose end surface defines a part of the intermediate fluid chamber. The diameter of the land portion is chosen to be the same as the diameter of the plunger, so that the sum in volume of the electromagnetic section fluid chamber and the intermediate fluid chamber can be kept invariable regardless of movement of the plunger. A supply/drain passage is further provided to permit the oil around the solenoid-operated valve to be charged into the rear end fluid chamber or discharged therefrom upon movement of the plunger.

Solenoid-operated valve

An electromagnetic drive device for lineally reciprocatilvely moving an operating member like a spool of a spool valve is reduced in the manufacturing cost without being degraded in its operational performance. In the electromagnetic drive device, a stator body is excited by an electromagnetic coil to axially move a plunger guided in an inner bore of the stator body, against the resilient force of a spring. The stator body is constituted by arranging a plurality of core portion annular plate elements made of a magnetic material, a plurality of yoke portion annular plate elements made of a magnetic material and a plurality of non-magnetic portion annular plate elements made of a non-magnetic material and placed between the core portion annular plate elements and the yoke portion annular plate elements and by piling up and bodily joining these annular plate elements in axial alignment with one another. Each of the annular plate elements is provided with plural embossed portions each of which is half-blanked to be prominent at one surface side and hollow at the other surface side. The embossed portions formed on each annular plate element are fit at the prominent surface sides thereof respectively in the hollow surface sides of the embossed portions formed on another annular plate element, so that all the annular plate elements can be bodily joined in axial alignment with one another.

Electromagnetic drive device

An electric power steering device in which a motor shaft and a rack bar form a diagonal intersection. The power transmission includes: a drive gear rotating in tandem with the motor shaft and forming a bevel gear with linearly extending teeth; a ball screw mechanism disposed co-axial with the rack bar and converting a rotational motion to a linear motion; and a driven gear rotating in tandem with a nut of the ball screw mechanism, meshing with and moving in tandem with the drive gear, and forming a bevel gear with linearly extending teeth. The drive gear and/or the driven gear can be adjusted so that backlash between the two elements can be adjusted in a continuous, non-stepped manner.

Electric power steering device

In a power steering apparatus having a control valve with a first control valve portion and a second control valve portion to enhance rigidity of a steering operation, an amount of an overlapping portion of an overlap variable orifice is designed larger than an amount of an unlapping portion of an untapped variable orifice in the control valve because of dispersion during manufacture. When the overlap variable orifice finishes overlapping, the unlapped variable orifice has already started unlapping. Therefore, since the overlap variable orifice and the unlapped variable orifice never become unlapping form simultaneously regardless of the dispersion, the control valve is capable of minimizing a difference of the flow between a plurality of the second control valve portion. As a result, the power steering apparatus relative to the invention prevents enlargement of noise caused by an unbalance of the flow between a plurality of the second control valve portions in the control valve.

Power steering apparatus

In a power steering apparatus comprising a pump, a reservior, a power cylinder having two opposite chambers, and a rotary control vale, the rotary control valve consists of a first control portion which communicates between the pump and the reservior, and a second control portion which communicates not only between the pump and the reservior but also with the power cylinder. In the first control portion, each of four underlapping variable orifices is so provided as to take the form of underlap in itself. In the second control portion, two underlapping variable orifices are provided on the side of the pump, and besides each of two overlapping variable orifices is so provided as to take the form of overlap in itself on the side of the reservior. In this manner, while a steering wheel is operated within a predetermined angle, an opening area of the overlapping variable orifice changes little. When the steering wheel is operated beyond the predetermined valve, the opening are increases sufficiently according to steering operation. As a result, a differential pressure between the chambers is prevented from originating at and around the neutral position of the steering wheel. Consequently, as for steering feeling, the rigidity of the steering operation at and around the neutral position is enhanced, and furthermore, a beginning point where the power assist is produced by operating the steering wheel from its neutral position is distinguished.

Power steering system including a rotary control valve with multiple

A hydraulic power steering apparatus includes a fluid pump, a power cylinder, a reservoir, and a control valve connected to the pump via a supply passage including a high pressure hose and connected to the reservoir via a drain passage. The power steering apparatus also includes a bypass passage provided between the supply passage and the drain passage, and a check valve which is disposed in the bypass passage to allow operation fluid to flow only in a direction from the drain passage to the supply passage. The power steering apparatus can supply a sufficient amount of operation fluid to the power cylinder even when a steering wheel is abruptly turned or when an opposing force is input from a tire.

Hydraulic power steering apparatus

A hydraulic power steering apparatus includes a motor-driven pump which discharges pressurized working fluid at a flow rate proportional to the rotational speed. A load-pressure responsive valve is connected to a discharge passage to which the pressurized fluid is discharged from the pump. The load-pressure responsive valve bypasses the pressurized fluid to a reservoir when the control valve is in a neutral state, thereby reducing the amount of the pressurized fluid supplied to the control valve, and increases the amount of the pressurized fluid supplied to the control valve when the load pressure of the pump increases upon operation of the control valve. With this control, the energy consumed by the pump can be reduced.

A power steering apparatus is composed a fluid source for discharging pressurized fluid, a power cylinder, a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid from the fluid source, and a reservoir. The control valve has a first control portion for controlling the flow of pressurized fluid from the fluid source to the reservoir, and a second control portion for controlling the flow of pressurized fluid to the power cylinder. The first control portion has four paths communicating with the fluid source and the reservoir, and each of the four paths is formed with a center-open variable orifice which opens when the control valve is in a neutral state. The second control portion has two supply paths communicating with the fluid source and a pair of chambers of the power cylinder, each of the two supply paths is formed with a semi-center-open variable orifice which opens when the control valve is in the neutral state, and two drain paths communicating with the chambers of the power cylinder and the reservoir, each of the two drain paths is formed with a center-closed variable orifice of which closes when the control valve is in the neutral state.

A hydraulic power steering system includes a pump, a flow control valve, and a bypass control valve. The flow control valve responds to a pressure drop across a metering orifice disposed in a fluid supply passage so as to control the flow rate of operating fluid by bypassing a part of the operating fluid to a reservoir. A spring chamber of the flow control valve is connected to the supply passage through a control orifice. The bypass control valve is disposed between the spring chamber and the reservoir so as to increase the amount of bypassed fluid by controlling the pressure in the spring chamber. The bypass control valve has a control spool, a load pressure introduction port connected to the upstream side of the control orifice for leading the load pressure to a first end of the control spool and a pilot port connected to the downstream side of the control orifice for leading the pressure in the spring chamber of the flow control valve to a second end of the control spool. Moreover, a pressure receiving area of the second end of the control spool is smaller than that of the first end of the control spool. Accordingly, a spring having a small spring constant can be used in the bypass control valve, even when the control spool is controlled within a short stroke. Further, the control spool, the load pressure introduction port, and the pilot port are formed in a sleeve.

A power steering apparatus comprises a fluid source for supplying pressurized fluid, a power cylinder having a pair of fluid chambers, a control valve, and a drain control mechanism. The control valve is composed of first and second control portions. The first control portion has four paths connecting the fluid source and the reservoir, and each of the four paths is formed with a variable orifice of center-open type. The second control portion has two supply paths communicating the fluid source with the fluid chambers of the power cylinder, each of the supply paths being formed with a variable orifice of center-open type, and two drain paths communicating the fluid chambers with the reservoir, each of the drain paths being formed with a variable orifice of center-closed type. The drain control mechanism is responsive to differential pressure between the fluid chambers of the power cylinder to control the communication of one fluid chamber under high pressure with the reservoir, and is responsive to a vehicle speed to control the communication of both fluid chambers with the reservoir.

A power steering apparatus having a fluid source for discharging pressurized fluid, a power cylinder, a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid from the fluid source, and a reservoir. The control valve has a first control portion for controlling the flow of pressurized fluid from the fluid source to the reservoir, and a second control portion for controlling the flow of pressurized fluid to the power cylinder. The first control portion has two paths connecting the fluid source and the reservoir, each of the paths being formed with at least one variable orifice of a center-open type which opens when the control valve is in a neutral state. The second control portion has two supply paths communicating with the fluid source and a pair of chambers of the power cylinder, each of the supply paths being formed with a variable orifice of a center-close type which closes when the control valve is in the neutral state, and two drain paths communicating with the pair of chambers and the reservoir, each of the drain paths being formed with a variable orifice of a center-open type which opens when the control valve is in the neutral state.

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Hekinan, Japan

Mikio Suzuki